I put some comments on a photo of the F158 multiplexer's vicinity that SlateBlue send me.

You can see that _DSPDS is quite far away. If I were the designer of this board I would use _DPSPS which is nearer to the decision logic.

You can also see that there is a lot of stuff going on beneath the F158 multiplexer. But important connections are not made: _DSPPS goes to a dead end. Same for the _Za output.

Some kind of cascading was obviously planned - maybe for other types of memory chips. S goes via a 10 Ohm resistor to I0a (strange). And _Za would go via a resistor to an input on the North side of the multiplexer.

Another sweep with the multi-meter yields no new information. Pins 3, 10, 11, 13, & 14 of the multiplexer have continuity to GND. Pins 4, 9, & 12 of the multiplexer are open. Pin 42 of the SIMM appears to be unused. I have no valid guesses here; this is the information I have found.

Section DSPDOC/maclib contains a list of the routines in the dsp
assembly-language macro library. These routines allow the user to
quickly write custom dsp software on top of standard io and
computational functions.

HOST C LIBRARY

Section DSPDOC/clib contains a list of the routines in the host C
library. (Since there is currently no C compiler for the dsp,
references to C software always refer to software running on the
host.) Many of these functions were created from corresponding dsp
macros using the program dspwrap. The general operation of such
functions is to download a dsp program to the dsp, along with the
user's supplied arguments, and initiate execution on the dsp.

HOST OBJECTIVE C LIBRARY

Section DSPDOC/objclib contains a list of the objects in the Objective
C object library. The dsp objects facilitate user interface design
and provide more intelligent software interfaces to the functions in
the host C library.

EXAMPLE APPLICATIONS

Some applications are included to illustrate use of these tools:

Music - Generate music algorithmically for dsp orchestra
MidiPiano - Play piano samples from main memory in real time
Spectrogram - Display spectrogram of sound input in real time

SYSTEM INTERFACE
äFollowing the example applications, the details of the interface
between the host processor (Motorola 68030) and the dsp (Motorola
DSP56001) are described. In particular, the dspwrap program is
described which makes a host C function from a dsp assembly-language
macro.

Off-chip DSP memory on the NeXT machine exists in two address ranges, each of which spans all of external memory. In the first address range (8K to 16K), x, y, and p memories are overlaid, that is, an external memory reference points to the same off-chip location regardless of the memory space specified. Note that in this address range, there is no l memory space support. (The high and low word are mapped to the same word.) In the second address range, 40K to 48K, x and y are split into separate 4K partitions, and p is overlays the entire 8K. This address region allows external l memory use, and supports algorithms (such as the Motorola benchmarks involving complex data) which expect x and y memories to be physically separate.

I don't know if this translates to 96kB, but i think i got my information from there.

Subject: L10. How to expand DSP memory?
The Speech Recognition Lab at San Francisco State University has developed a DSP memory expansion board for the NeXT computer that provides the maximum memory supported by the DSP56001 processor. We are now offering this board to those whose are interested in high-performance custom DSP development.

The board is a 576KB DSP expansion memory board organized as three non-overlapping 192KB banks: X-data, Y-data and Program. The board uses relatively fast (lower than 35ns) SRAM. This board compares with NeXT's DSP memory expansion board, which offers only 96KB in an imaged memory configuration.
The board is a high-quality, 4-layer board, open-circuit tested prior to assembly. It fits into the DSP memory daughterboard slot on all NeXT machines.
The price will be $600. Please let us know if you are interested. Delivery will be in about 3-4 weeks.
Contact Tom Holton (th@ernie.sfsu.edu). E-mail is prefered. The address is:
Tom Holton
Division of Engineering
San Francisco State University
1600 Holloway Avenue
San Francisco, CA 94132
415 338 1529 (phone)
415 338 0525 (fax)

Note: Because we've organized our memory as three separate (non-overlapping) banks (X, Y and P) of 192KB apiece, none of the DSP memory image functionality provided by NeXT with its existing 8K base configuration, or its 96KB DSP expansion module is supported. While we cannot guarantee that every existing DSP application ever written will be plug-and-play compatable with our DSP expansion memory, we are not aware of any existing applications that use the image functionality. The MusicKit, and demo programs that use the DSP, such as Mandlebrot and ScorePlayer, work fine with our memory module.

I just received this and detailed the fax

Hi.

This email was forwarded to me.

It has been a very long time since this board was built and we probably purged anything pertaining to this part number.

I have printed what you sent with your email but it's confusing what the actual part number is. Can you please confirm the part number and which company it was actually ordered under?

Hello Lisa: Thank you in advance for your time, the part number appears to be for manufacturing a 128K * 4 Memory Expansion Module 576Kb DSP expansion module

Apologies as it is an old doc but provides some good clues! 64pin with 6 Micron MT5C1008-35, Hex Invertors and Capacitors mounted on 4 layer board so it works in an old expansion DSP Expansion slot in a NeXT computer .

It would have been commissioned for San Francisco State University 8/20/92 or 2/5/93 .... to Rev's A 8/20/92 and B 2/5/93 probably with in 90 days

The Document I referenced in the previous email was for SFSU. It was drawn up by Silicon Valley Consultants , Leopard Design 415/338-1997 and a 3rd party manufacturer and as Cordova Circuits , is actually on the fax , I'm hoping you all may still have it on film .

pages 1,2,3 are the schematics with part numbers for the physical chips

pages 4,5,6,7,8 show the layers and latout of the 4 layered pcb board for the ram DSP expansion

$
9,10,11,12 look to have been faxed to or from phone 408 946 3252 Cordova Circuits as an approved production run in reverse order ,
These might be drawings from Cordova > Assembly Drawing NeXT Display Memory Expansion drawn by initials SVC
apologies on this I'm going from an old archive document and trying to figure it out....
12 = page 2 original fax
11 = page 3 original fax
10= page 4 original fax
9 = page 5 original fax

NeXT was Steve Jobs interim company between his stints at Apple , they only made about 20000 NeXT computers and I'm the last guy on the planet still maintaining them full time it is fun.

We have devoted group of NeXT computer owners and forum members that want to reproduce these chips to fill the empty expansion slots on the motherboards!

So hopefully Cordova Circuits can help us out !

We have many of the original NeXT engineers helping as well

I found an FAQ and will try to contact Professor Holton as well , he is still there so hopefully I'll find additional info as well!

Best Regards Rob Blessin

PS Here is an FAQ I found:
Subject: L10. How to expand DSP memory?
The Speech Recognition Lab at San Francisco State University has developed a DSP memory expansion board for the NeXT computer that provides the maximum memory supported by the DSP56001 processor. We are now offering this board to those whose are interested in high-performance custom DSP development.

Note: Because we've organized our memory as three separate (non-overlapping) banks (X, Y and P) of 192KB apiece, none of the DSP memory image functionality provided by NeXT with its existing 8K base configuration, or its 96KB DSP expansion module is supported. While we cannot guarantee that every existing DSP application ever written will be plug-and-play compatable with our DSP expansion memory, we are not aware of any existing applications that use the image functionality. The MusicKit, and demo programs that use the DSP, such as Mandlebrot and ScorePlayer, work fine with our memory module._________________Rob Blessin President computerpowwow ebay sales@blackholeinc.comhttp://www.blackholeinc.com
303-741-9998 Serving the NeXT Community since 2/9/93

The Document I referenced in the previous email was for SFSU. It was drawn up by Silicon Valley Consultants , Leopard Design 415/338-1997 and a 3rd party manufacturer and as Cordova Circuits , is actually on the fax , I'm hoping you all may still have it on film .

pages 1,2,3 are the schematics with part numbers for the physical chips

pages 4,5,6,7,8 show the layers and latout of the 4 layered pcb board for the ram DSP expansion

$
9,10,11,12 look to have been faxed to or from phone 408 946 3252 Cordova Circuits as an approved production run in reverse order

[quote="bobo68"]Interesting! Where is the fax/doc you are referring to?

[quote]
The Document I referenced in the previous email was for SFSU. It was drawn up by Silicon Valley Consultants , Leopard Design 415/338-1997 and a 3rd party manufacturer and as Cordova Circuits , is actually on the fax , I'm hoping you all may still have it on film .

pages 1,2,3 are the schematics with part numbers for the physical chips

pages 4,5,6,7,8 show the layers and latout of the 4 layered pcb board for the ram DSP expansion

$
9,10,11,12 look to have been faxed to or from phone 408 946 3252 Cordova

This is interesting , I'm wondering if we would be able to program one of these to emulate a dsp expansion module any thoughts? https://www.bigmessowires.com/mac-rom-inator-ii/ after reading more on this so I'm guessing it may be possible to create custom NeXT rom chips that would support more ram memory
Based on this awesome The pre-programmed ROM image also makes the Mac 32-bit clean, enabling it to use more than 8MB of RAM natively without the need for special system enablers or extensions. Some older Macintosh models like the IIx, IIcx, and SE/30 have stock ROMs that are “dirty”, meaning they can’t support 32-bit addressing without ROM patches. Using the Mac ROM-inator II and the pre-programmed ROM image, the Mac SE/30 can support up to 128MB of RAM!_________________Rob Blessin President computerpowwow ebay sales@blackholeinc.comhttp://www.blackholeinc.com
303-741-9998 Serving the NeXT Community since 2/9/93

Last edited by Rob Blessin Black Hole on Sun Jun 18, 2017 1:57 pm; edited 1 time in total

Don't know if it makes sense to go that route. The DSP module is just a RAM module and that's all that's needed. The ROM-inator is a Flash module meant to replace a Mac II ROM module in order to be able to replace ROM contents relatively easy. It's a different application.

Don't know if it makes sense to go that route. The DSP module is just a RAM module and that's all that's needed. The ROM-inator is a Flash module meant to replace a Mac II ROM module in order to be able to replace ROM contents relatively easy. It's a different application.

They are both 64 pin simms and I'm wondering it is flash memory already in production highly customisable and modifyable , I have an Apple rom here and it fits in the DSp expansion slot . The other thing that is neat is this "The pre-programmed ROM image also makes the Mac 32-bit clean, enabling it to use more than 8MB of RAM natively without the need for special system enablers or extensions. Some older Macintosh models like the IIx, IIcx, and SE/30 have stock ROMs that are “dirty”, meaning they can’t support 32-bit addressing without ROM patches. Using the Mac ROM-inator II and the pre-programmed ROM image, the Mac SE/30 can support up to 128MB of RAM! "
So in theory we should be able to program a rom possibly that accepts higher simm chips I have a rom burner so if it is modifying the code in the rom.bin to burn the enhanced rom just need to know what to modifiy? Also I have often wondered if older NeXT hardware can be modified to work with adb components by modifying the rom.

This one looks promising for modifying our current NeXT roms
https://www.bigmessowires.com/mac-rom-inator/
perhaps testing with a daydream box , I have one to see if higher value simms will boot a NeXT into Daydream , we now have dark matter and previous so maybe it is possible to test it
in theory on Previous as well ? The other question would be does an Apple 512k rom work for memory expansion on a NeXT the one I have does not?_________________Rob Blessin President computerpowwow ebay sales@blackholeinc.comhttp://www.blackholeinc.com
303-741-9998 Serving the NeXT Community since 2/9/93

Yep, I know the value of something like this for a Mac as a *ROM replacement*. I have a few classic Macs here. The ROM-inator is highly customizable in the sense that you can upload different ROMs into the Flash memory. It is not highly customizable in the sense of emulating different SIMM pin functions, RAMs, etc.

The DSP memory expansion has nothing to do with this. It gives the DSP more (empty) *RAM*.

That said, the *ROM* of the NeXT computers could probably be replaced by some kind of Flash ROM-inator.

Hello NeXT Community: So I no have the NeXT DSP memory expansion module and would like to proceed with using it to make modern clones of the chip. Any thoughts? I know Cordova electronics said if they have the chip the would theoretically be able to make duplicates. I bought the chip for $225 and will basically donate it to the NeXT forum community so we can all figure this one out sound good , as it'll be fun to populate those open slots in everyone's NeXT .... Best Regards Rob Blessin_________________Rob Blessin President computerpowwow ebay sales@blackholeinc.comhttp://www.blackholeinc.com
303-741-9998 Serving the NeXT Community since 2/9/93